Paper money and merchandise coupons, gift certificates, event tickets, securities, and the like have conventionally been used in the form of a printed matter as indexes of the levels of value of the economy, distribution, and markets and in order to smooth these. These printed matters usually are pieces of paper or the like, which bear particular matters, or to which particular matters have been imparted by printing, etc. Such printed matters are lightweight and small and are convenient for carrying, storage, and use. However, because materials familiar to the public, such as pieces of paper, are used, there have been cases where such printed matters are illegally copied or counterfeit.
For the purpose of preventing such counterfeit, the imprint of a seal possessed by the publisher, a signature, a watermark, and the like have been used from long ago as means for identification. However, these identification means are easily faked by persons having a special skill, or by means of the copying/printing technology that has progressed recently, etc. Although such means are still in use at present, the actual reliability thereof is decreasing. In recent years, a bar code mark or the like has been used. However, since this bar code mark is an inorganic pattern composed of lines, it impairs the elegant image of the security and, further, has a drawback in that it is easily faked by the advanced technology of image analysis, copying, printing, etc.
Furthermore, a technique is being employed in which the security is produced as a magnetic card or a printed matter obtained through printing with a magnetic ink, and the magnetism thereof is identified. However, the magnetic card and the printed matter produced with a magnetic ink have had problems in that they have an impaired appearance due to the black or black-brown tone generally possessed by magnetic powders, and in that they are easily counterfeit because use of a magnetically identifying function is readily noticed. Still further, a technique which is being employed is to incorporate a fluorescent substance into a printing ink and identify the visible to fluorescent color of the printed matter. However, this technique, in which a visible to fluorescent color is identified, is intended to be used usually in such a manner that the printed matter is illuminated with a fluorescent lamp, and the resultant color development is identified with the naked eye. Hence, this technique is unsuitable for use in strict genuine/counterfeit discrimination.
As described above, the conventional techniques for genuine/counterfeit discrimination are still unsatisfactory.